Numerous athletic games require the use and swinging of an athletic implement that has a head portion and a shaft. Examples of such athletic implements include golf clubs, tennis rackets, polo sticks and baseball bats.
One of the problems that has long existed in these athletic endeavors is the accuracy of the control of the athletic implement when it is being swung by the player. For example, in the game of golf, loss of control of the golf club occurs during the back swing when the head portion deviates from the plane in which the club should remain. As a result, there is a disadvantageous loss of control of the club which prevents golfers from experiencing optimum results in striking the golf ball during the forward portion of the swing.
Golf clubs have been designed which add weight to the head end of the club, but there are deficiencies and attempts to overcome such deficiencies with redistributing the weight along the device have been proposed in the prior art. Thus, attempts have been made to add weight adjacent to the hand held portion of the device to improve control of and the resulting accuracy of the movement of the athletic device. When this is done, it is possible to control the implement more precisely and maintain it in the desired plane of movement when the implement is swung in the forward direction to make contact with an object.
Of even greater significance with golf clubs and the problem of weight distribution is the advent and use of new high-technology golf shafts made of graphite, graphite-boron, or metal-graphite-boron composites. These new golf shafts, which are manufactured with precise predictability with respect to flexibility and flex point location along the shaft, have also added a new consideration called torque, which is the twisting of the shaft about its longitudinal axis, a dynamic factor which heretofore did not exist with all-metal golf shafts. This torquing action has created a wide variety of choices for golfers of all skill levels in selecting the appropriate club shaft for improvement of their game, and has complicated the issue of club weight and balance. Additionally, because of the lighter weight of the graphite or graphite-boron composite shaft, the club head may be made heavier while maintaining the same overall club weight, a distinct advantage in the area of control and distance.
The current theories of golf ball distance and control predicates itself on lightness of the shaft and club head weight and mass along with the increased speed of the head at time of impact with the ball. The mass, weight, speed equation as relates to propelling the golf ball is the primary basis for design of modern day golf clubs using high technology composite shaft construction techniques. However, as the weight of the club head is increased, club head speed at point of contact is reduced. It is therefore necessary to rebalance the club by backweighting.
U.S. Pat. No. 2,051,083 to Hart discloses what is described as a golf shaft balancer which in effect is a weighted insert adapted to pass into a hollow shaft and be longitudinally positionable as well as rotatable within the shaft to give the shaft a desired feel. The balancer is described as being particularly useful in putters which in fact do not have an extended amount of flex and virtually no torque when used.
U.S. Pat. No. 1,210,182 to Lynch also discloses a solid club in which a lead weight is supported at one end and enclosed by a ferrule or cap affixed to the end of the solid shaft club.
U.S. Pat. No. 3,075,768 to Karns provides a compartment in one end of a golf shaft in which is disposed a separate container or sack containing weighted particulate material. Alternatively, a plug is disposed within the shaft and frictionally or adhesively retained in place on top of which is positioned the particulate or shot material which is to be retained in place by a plug or adhesive, followed by affixing the actual grip to the club shaft.
U.S. Pat. No. 4,461,479 to Mitchell offers an insert which consists of a fixed unit of weight with a vibration deadening sleeve which inserts into the shaft prior to affixing the grip to the club shaft, a technique not too dissimilar than Karns above.
U.S. Pat. No. 4,600,195 to Hunter suggests cutting off the end of the grip to expose the hollow shaft and adding an adapter which glues into the shaft. By adding an unlimited number of weights to the adapter, which extends externally behind the gripping portion of the club, improvements are realized.
U.S. Pat. No. 4,690,407 to Reisner goes even further in molding the golf grip around a segmented section of fixed weight and this assembly then is the final grip which is affixed to the free end of the club. U.S. Patent No. 4,988,102 also to Reisner modifies the design of the segmented weight in the '407 Reisner patent to improve attachment characteristics when affixed to the golf shaft.
Great Britain Patent No. 194,823 to Stirling discloses improvements in golf clubs and, more particularly, shows adjustable weights provided in an axial bore in the handle or shaft of the club.
While the above documents disclose attempts to balance an athletic implement shaft of the type that is swung, particularly a golf club, none of the techniques shown or embodiments disclosed have solved the real problem of the backweighting technique whereby the weights are simultaneously physically functional, not disconcerting to the golfer, readily interchangeable but still within the rules of the United States Golf Association pertaining to the golf grip, and can be varied on a club-by-club basis through dynamic performance testing by the golfer and can be done in a quick, efficient manner without a golf club technician's assistance.
In the cited documents, weights of fixed value are applied by use of a mechanical or adhesive means prior to affixing the grip to the club, or by a destructive means of cutting off the end of the grip in order to alter the balance point. The technique of adding the weights prior to affixing the grip are based on a calculation of presumed best weight rather than through dynamic performance testing by the actual user of the golf club for optimal results in accuracy and distance on a club-by-club, player-by-player basis, as is with the instant invention.
Hart's insert requires that it be glued or mechanically held in place at some point along the golf club shaft. This solution would have been functional with metal shafts but is not compatible with graphite-composite golf shafts in that a stress point is created altering the entire design characteristics and creating a point of potential breakage of the shaft when it strikes the ball. Modern club heads are purposely manufactured with a twenty degree reaming of the inside of the ferrule rather than a parallel snug fit which causes a stress point and point of breakage. Graphite shafts, when scored, will break in a manner similar to window glass when scored with steel and subjected to pressure.
Lynch, Karns, and Mitchell all require affixing the grip after the weight is added. Reisner has the fixed unit of weight as an integral part of the grip on a one-weight-one-grip-fits-all basis. Hunter advocates cutting off the ends of all golf grips, adding an adapter section by gluing in place, then adding weight after weight to achieve the desired end result.
The flaws in Lynch, Karns and Mitchell are obvious in that all weighting is of a fixed amount and the grip is installed after the weight is added. Testing of the club must wait from 4- to 24-hours and if not correct or best suited for the golfer, the grip must be removed, which is a destructive process, a new weight inserted, a new grip installed, and a new waiting period starts again. This is not a desirable situation when a golfer is on the practice range with a tee time in one hour.
Reisner seeks a compromise solution to the problem, but declares that one grip with the same weight will do the job for all clubs. It is highly unlikely that a fixed unit of weight would produce the same results on such a broad range of players as a hard-hitting low-handicapper compared with a slow-swinging lady-senior. Perhaps a mid-range golfer could use the same weights, but the problem of the same weight for each club not being the ideal solution remains unsolved in the Reisner patent. Additionally, there are a considerable number of different types of golf grips available to the golfer, who selects them on size and feel. The Reisner grips would have to be molded into every possible type of grip for both men and ladies club in two shaft diameters of 0.580" or 0.600" and, if a choice of weights were made available, the sheer inventory of golf grips required by the industry would make the use of the Reisner technique a logistical and inventory nightmare from manufacturer to retailer or custom clubmaker. Additionally, the variety of club head weights and shaft combinations dictate that a fixed-weight concept is not the solution to optimization of golf club performance.
Hunter carries the concept to extremes and with the current technology of heavier club heads on lighter shafts, the length of weight to be added behind the grip could exceed the length of the grip itself, even to the point of hitting the golfer's body when the club is swung back. Hunter's arrangement of back weights creates a problem rather than solves one with today's golf club composite materials applications. The Hunter design is disconcerting to the golfer, mechanically increasingly unstable with a great number of weights, and adds weight in a manner that is much too far away from the butt end of the club to be effective. A player would be better off with longer shafts, longer grips and holding the club lower down the shaft than by using the Hunter extensions. It is not incidental that manufacturers of graphite composite shafts recommend cutting the butt end of the shaft 1/2" to 1" longer than standard fit for the golfer to help offset the imbalance caused by the heavier head and lighter shaft and allow for greater club head speed at impact.
The device of the Stirling patent is also unsuitable for modern day golf club design since the device is directly attached to the handle and the weights are in direct contact with the handle. This design makes it difficult to adapt to different clubs and is conducive to imparting vibration to a user via the weights.
As such, a need has developed to provide an improved golf grip with adjustable back weighting capability that overcomes the disadvantages of the prior art as discussed above. Responsive to this need, the present invention provides such a grip which enables a user to fine tune a given athletic implement for the user's ability.